High-rise Residential - Favored retrofit strategies & stories

For those conducting energy audits and developing retrofit work scopes for high-rise apartments, please share your experiences in this thread. Successful methods, pitfalls and complete disasters are all fair game for sharing with the group.

Since there are distinct difference between high-rise and low-rise strategies, let's keep our discussion here only on high-rise. Low-rise thread stories go here.

The Aldes CARs are effective as long as you can maintain the recommended static pressures in the stack, which are pretty high. They will require maintenance over time because they can get clogged with dust and gunk.

So, we just got a fine surprise -- garbage chutes! In a half-dozen high rise buildings (12 to 20 stories) we are weatherizing, the garbage chute runs the height of the building, right up the core. Needless to say, at 20 degrees F. outside, that chute has a breeze blowing up it that will lift lift card stock. We found Christmas cards jammed in a chute joint, 20 feet higher than any residential floor in the building. Our energy model says (Milwaukee) that this exfiltration costs something north of $10k per winter!

Turns out that NFPA codes say you CANNOT restrict the top of the chute. I found this out just as we were going to bid on the first big project where we identified this flaw. So you can imagine my displeasure when we found out we have to maintain an area equivalent to the full chute cross section that has to be open the air, and the chute restrictor we planned to install under the rain cap had to be scrapped.

But companies DO make an automatic (counterbalanced) door that can be installed at the bottom of the chute, just above the Dumpster. So we are going that route instead (I hope...) We'll see if it works!

Sorry, that ended up being a dry hole. The only door we found available is the "conventional" sliding fire-stop door required by NFPA code.

Jim Fitzgerald passed on to me some info about a retrofit he accomplished in a couple of buildings, where he convinced the local Code authority to let him install a small continuous fan at the top of the chute, and get control of it. When we looked at it, we decided that (in an ARRA project) we didn't have the time to engage that deeply with Code staff and try to implement his strategy.

We ended up instead weatherstripping all the chute doors and air sealing the garbage room as tight as we could. (Choke off the stack effect from the bottom, rather than the top.) I hope to get back into (on top of) some of the buildings this winter and see if that's working.

Yes. It is becoming clear that we will never get energy-efficient MF housing until we start measuring the performance of the building shell. Although, as far as blower door work in MFBs to date, "high rise" may be stretching it a little--current work has mosly been in more like "mid-rise" buildings. But that's fine -- after all, there are a LOT more three-story apartments than 20 stories.

Wisconsin has their Focus On Energy program doing a lot of blower door tested air sealing in 4-8 unit buildings. And they have been doing some new construction infiltration testing on (roughly) 50-unit three-story buildings. I have done blower door work in buildings up to nine stories over the last few years.

City of Seattle is bringing on line a new code that looks like it will require air barrier design and blower door testing in new buildings governed by their commercial code. Last I knew, this was still in flux; the testing provisions may yet be diluted out of the code to avoid getting too far out in front of the capabilities of the T&B industry.

MY estimate is that more than 100 apartment buildings have been tested in Wisconsin--this stuff is getting VERY do-able. I just don't know what it will take to get other energy efficiency folks starting to add this to their toolbox.

There are a couple of new software tools (became available just in the last half year or so) that make it a LOT easier to coordinate multiple blower doors and test larger buildings. I will be presenting on this at ACI San Francisco. And TEC will be doing a two-day course there (the Monday and Tuesday before the core conference) on using their multi-fan software with Minneapolis blower doors to test large buildings.

We have tested a few 19th century town hall buildings with towering windows. One tecnique we used was to seal up a couple of windows with poly and tape and compare pre and post numbers. It is a rough way to get an idea how much the windows are contributing to infiltration.